Notation

Definitions

The domain of a Binary Function is the set of all ordered
pairs (x, y) that are permissible values for its arguments.

The range of a Binary Function is the set of all possible value that it
may return.

Valid expressions

Name

Expression

Type requirements

Return type

Function call

f(x,y)

Result

Expression semantics

Name

Expression

Precondition

Semantics

Postcondition

Function call

f(x,y)

The ordered pair (x,y) is in f's domain

Calls f with x and y as arguments, and returns a value of type Result[1]

The return value is in f's range

Complexity guarantees

Invariants

Models

Result (*)(X,Y)

Notes

[1]
Two different invocations of f may return different results, even
if f is called with the same arguments both times.
A Binary Function may refer to local state, perform I/O,
and so on. The expression f(x,y) is permitted to change f's state.